Chat, in general, tends to have very limited additional paralinguistics (tone of voice, facial expression, body posture) and at the risk of belittling other users' intelligence, I generally try to express my opinion with words rather than ironic pose.
That's actually quite different from the way most of us speak (er, like on the phone or in person), and it's nice to see some discussion around that.

My jottings during that same discussion include the following notes (consider these perhaps Apocrypha to go with ferrency's Scripture, and note that they are loosely based on decent rules for a school prank):

Thou shalt identify Irony with Emotive Symbols, with "j/k", or with the Emotive Tags <irony></irony>.

When demonstrating how Code can be Abused, thou shalt demonstrate Abuse by Embarrassment, and not Abuse by Destruction.

If Thou be a Scourge to the Newbies, thou shalt bring Confusion and Disarray but bring not Destruction nor Mayhem.

When putting a smiley right before a closing parenthesis, do you:

Use two parentheses: (Like this: :) )
Use one parenthesis: (Like this: :)
Reverse direction of the smiley: (Like this: (: )
Use angle/square brackets instead of parentheses
Use C-style commenting to set the smiley off from the closing parenthesis
Make the smiley a dunce: (:>
I disapprove of emoticons
Other